"The bottom line is, under the Affordable Care Act, the share of Americans with insurance is up, the growth of healthcare costs is down, and hundreds of millions of Americans who had insurance have new protections," Mr Obama added.

Re-fighting political battles

The figure of eight million people enrolled in health insurance through the law's online marketplaces beats the government's initial forecast of seven million sign-ups.

Mr Obama said healthcare spending had risen more slowly than at any time in the last half century.

Republicans remain united in their opposition to the 2010 law and have battled to repeal or undermine it at every turn.

The Republicans have indicated they will stoke lingering public doubt about the law in their efforts to hold the House of Representatives and wrest control of the Senate from Mr Obama's Democratic Party in the November midterm elections.

"I think we can agree it's well past time to move on as a country," Mr Obama said of Republican efforts to repeal the healthcare overhaul.

"These endless, fruitless repeal efforts come at a cost," he added of the 50 symbolic votes the Republican-led House has held on the issue.

"The [law] is working and I know the American people don't want us re-fighting the settled political battles of the last five years."

The law, known to its detractors as Obamacare, passed in 2010 with no Republican votes. It is aimed at extending health insurance to the roughly 48 million Americans who did not receive it through their employers, the government, or a privately purchased plan.

The law remains controversial among the American public, as some people have seen their insurance costs rise or their old health plans cancelled, while others object to having to purchase insurance at all.

Republicans see it as inappropriate government intrusion into the healthcare industry. US residents face a tax penalty next year if they do not have some form of health coverage.

"It's long past time for Washington Democrats to work with us to remedy the mess they created," Republican Senate minority leader Mitch McConnell said on Thursday.

"That means repealing this law and replacing it with real reforms that actually lower costs," he added.